Wire clamp



Feb. 26, 1963 w. E. HEDDERICH ETAL 3,

WIRE CLAMP 3 Sheets-Sheet 1 Filed June 15. 1960 m; M-zuqm (5' Weddericl1 deal cflfiannev kgq Carl 3: 5 Carlson,

4QLOK YL6OY Ala-4 Lamb... CATTORNEIY/ aired Stats The present inventionrelates broadly to wire clamps and more specifically to clamps findingparticular, but not necessarily exclusive use for holding steel wire orrods under tension during the manufacture of prestressed concrete beams.

In the production of prestressed concrete structural shapes such asbeams, the concrete is provided with steel reinforcing members which arepretensioned while the beam is being cast and are held in this tensionedcondition when the concrete has hardened. For the manufacture ofprestressed concrete beams which are extremely large, such as the typesnow widely employed in bui1ding construction, continuous castingmachines are employed which are capable of forming long lengths ofbeams. In apparatus of this character steel wire or rod is supplied froma continuous source such as a reel, and is fed through a tensioning andcut-off mechanism. During the casting of the beam, the pretensionedsteel wire must be clamped in place on both sides of the beam. Variousclamping mechanisms have been proposed for this purpose, although theresults have not been entirely satisfactory.

The general object of the invention is to provide a new and improvedwire clamp which is made from a small number of simply formed parts soas to be comparatively inexpensive, which is rugged and durable inservice use and which is easily assembled and disassembled for cleaning.

A more detailed object is to make the clamp from simple sliding blockswhich Wedge the wire between the jaws of the clamp and which aresecurely held in their operative positions even though they may beremoved without the use of special tools.

Another object of the present invention is to facilitate the insertionof the reinforcing wire into the clamps so that the castin operation canbe made substantially automatic and continuous and to provide a positiveyet readily releasable grip on the wire which positively holds the wirewhen it is under tension.

Still another object of the invention is to facilitate the cleaning ofthe component parts of the wire clamp by utilizing planer surfaces inthe construction thereof. A like object is to provide a wire clamp ofthe foregoing type'which has few movable parts thereby further reducingthe possibility of fouling and faulty operation caused by collection ofconcrete thereon and further facilitating the cleaning of the clamp.

A further object of the invention is to provide a clamp having theforegoing characeristics in which the active clamp surfaces areprotected against the entrance of concrete.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds taken in connection withthe accompanying drawings wherein:

FiGURE 1 is a perspective view of a concrete beam of the characterproduced by the mechanism with which the clamps embodying the presentinvention are employed.

PEG. 2 is afraginentary elevation view of a mechanism for tensioningreinforcing wire or rods in a concrete beam.

FIG. 3 is a section view taken substantially in the plane of line 3--3of FIG. 2 and illustrating a plan view of clamps embodying the presentinvention.

FIG. 4 is a section view through a clamp embodying the present inventiontaken substantially in the plane of line 4-4 of FIG. 3 and showing awire engaged by the clamp.

FIG. 5 is a view similar to FIG. 4 but illustrating the clamp in an openposition.

FIGS. 6 and 7 are section views similar to FIG. 5 but showing a clamp inpartial stages of disassem-bly.

FIG. 8 is a perspective view of the jaws of the clamp shown in FIGS.3-7.

FlG. 9 is a section View taken substantially inthe plane of line 99 ofFIG. 4 and illustrating the clamp operation.

FIG. 10 is a fragmentary section view similar to FIG 9 but showing theclamp in a fully released position.

FIG. 11 is a section view taken substantially in the plane of line 1111of FIG. 10.

FIG. 12 is a perspective view of the mechanism for clamping the jawsshown in FIG. 8.

Concrete beams, such as the type shown at 10 in FIG. 1, are cast in asuitable apparatus, the details of which have not been shown. Ingeneral, typical apparatus includes a mechanism for supplying andpretensioning steel reinforcing members 11 which are embedded in theconcrete beam. Because the concrete beams cast are usually quite long,the mechanism is supported on a gantry type carriage which straddles thebeam casting mechanism and travels on rails in traversing the length ofthe beam. A portion of such a mechanism is shown in FIG. 2, themechanism for engaging and gripping the free end of the reinforcingwires 11 being indicated generally at 14 and the wire supply, feed,cut-oif, and tensioning mechanism being indicated generally at 15. Somemeans, such as a feed screw 16 is usually provided for raisingand'lowering the mechanisms 14, 15'. The reinforcin rod or wire 11 isfed from a supply source such as a reel (not shown) and is cut to lengthas it is used.

For securely gripping the reinforcing wires or rods, an improvedclamping device is provided, a pair of such devices 2%, 21 being shownon opposite sides of the beam casting station, for use in conjunctionwith the wire tensioning mechanism in order to hold the pretensionedwires while the concrete beam is formed, which clamping devices arecapable of holding the wires positively .and surely during the castingoperation and can be readily released after the beam has set. The clamps2t), 21, are mounted adjacent the casting station on suitable supportssuch as spaced vertical l-beam posts 22, 23., Generally, asecond pair ofclamps 2d, 25 is provided at each station vertically displaced from thefirst pair so that a second set of reinforcing rods can be employed.This is important when, as shown in the drawings, the beams are castwith upper and lower pretensioned rods therein. Because the clamps 20,21, 24 and 25 are identical, only one will be described in detail, itbeing understood that the description applies as well to the remainingclamps.

Each clamp comprises a body or clamp body 28 mountable on the supportposts 22 (FIG. 3) and defining at each end a slot 29, 3d for receivingthe clamping mechanism proper. By forming the clampbody 23 with aclamping mechanism at each end and mounting it at its center on thesupport post, two reinforcing wires can be tensioned simultaneously. Inaddition, because two pretensioned wires are gripped at one time, thestructure is more rigid in that twisting of the support posts 22 isavoided. The clamp body 28 is secured to the support posts by suitablenut and bolt fasteners 31.

To grip the reinforcing wire 11, each clamp includes 3 two blocks 39 and40 disposed side by side in the slot 29. Opposed surfaces 41 and 42 ofthe blocks are serrated or knurled to bite into and securely grip thewire whereby the blocks constitute the jaws of the clamp. The upperedges of the blocks are charnfered to provide sloping surfaces 44 whichguide the Wire into the slot between the jaws and into position to begripped.

Normally, the block 39 abuts against the wall 32 of the slot 29 as shownin FIG. 4 and the block 40 is forced laterally toward the block 39 by awedge block 50. The latter also is disposed in the slot and acts betweenthe wall 33 and the back of the block 40. For this purpose, the back ofthe block 40 is formed with an inclined or tapered surface 48 whichbears against a mating surface 49 on the wedge 50 so that, as the wedgeis moved longitudinally to the left as viewed in FIG. 8, the block 40-isshifted laterally toward the block 39.

Depending from the ends of the block 39 are flanges 45 which are spacedapart a distance generally equal to the width of the clamp body 23 sothat they straddle the bottom wall 34 and prevent endwise shiftingof theblock 39 while permitting the latter to slide sidewise. Similar flanges46 depend from the ends of the block 40. The wedge 50 is longer than theblocks and also is formed-with depending flanges 52 which are spacedapart farther than the flanges 45 and 46 to permit limited endwisesliding of the wedge.

To prevent the blocks 39, 40 and 50 from being removed from the slot 29during normal service use, shoulder members or flanges 35 and 36 projectinwardly from the upper ends of the walls 32 and 33 respectively. Theflange 35 is comparatively short and projects in closely over the block39. The flange 36 fits closely over the wedge 50 and extends oversubstantially the full width of the latter. A third flange 51 projectsin from the upper end of the wedge and over the block 40. Thus, theflange 35 holds the block 39 in the slot, the flange 36 retains thewedge 50 and the flange 51 holds the block 40. These three flanges,together with the flanges 45, 46 and 52, serve the added function ofpreventing concrete from splashing onto the various sliding surfaces andthereby prevent the clamp from fouling.

The wire clamping action of the wedge block 50 and jaws 39 and 40 isillustrated in FIGS. 9, and 11. The wedge block is sufficiently long sothat it may be slid to one extreme and thereby release the jaws forseparation suflicient to permit the insertion or removal of areinforcing wire. shown in FIG. 9, the tapered surface 49 of the wedgeblock engages the corresponding surface 48 of the jaw 40 and therebyearns the jaws together into gripping engagement with the reinforcingwire 11. The serrated edges of the jaws bite into the wire and securelyhold the same, even when the wire has been placed under considerabletension.

According to another aspect of the invention, the sizes of the flanges35 and 36 are correlated in a novel manner with the sizes of the blocks39, 40 and 50 so that the blocks may be removed from the clamp body 28while normally being retained in the slot 29. For this purpose, thelength of the flange 35 is such that, when the narrow end portion of thewedge 50 engages the block 40 and there is no wire between the jaws, theblock 39 can be moved out from under the flange 35 as shown in FIG. 6and lifted out of the slot 29. In any other position of the wedge,however, the flange 35 holds the block 39 in place as illustrated inFIG. 6. After the block 39 has been removed, the block 40 may he slidout from under the flange 51 and lifted out of the slot 29. Next, thewedge 50 is moved over to the position shown in FIG. 7 in which it isalined with the space between the flanges 35 and 36. This space is madeslightly greater than the width of the wedge so that the latter may belifted out of the slot. The reverse procedure is followed to assemblethe clamp.

Upon movement to the other extreme, as i The cooperating taperedsurfaces between the wedge block and the wedge jaw are clearlyillustrated in FIG. 12. The slope of the tapered surfaces on the jaws issmall so that an extremely powerful clamping force can thereby beobtained for a relatively small closing movement of the jaws. It will beappreciated that the clamping and jaw mechanism at each end of the clampblock 28 is a mirror image of the other. With this construction themovable wedge blocks are towards the center of the clamp block andremain always at a substantial fixed distance apart. With this positionknown the clamp is admirably suited for use with an automatic clampingmechanism which can be stopped in front of the body and actuate bothsets of jaws at one time.

One illustrative mechanism for actuating and releasing the clamps isshown in FIG. 2. This mechanism comprises a hydraulic plunger mechanism55 having a member 55 on one end thereof engageable with :1 dependingflange 52 on the end of the wedge block 59. The plunger member 56 ispreferably formed with a slot which slides beneath and straddles theflange 52. The clamp is constructed to be actuated to clamp the wire bymoving the wedge block up as viewed in FIG. 9. In operation, the wirewill be fed across the beam mold and gripped in clamps 20 at one side ofthe beam. A tension of the desired magnitude will be applied to the wireand clamps 21 engaged to hold the wire in place. The wire is thensevered and the wire feeding and clamping mechanism will be moved to thenext or to a lower station.

When the beam has been cast, the clamps can be readily released byengagement with the mechanism 55. This mechanism pushes on one end ofthe wedge block, preferably with a hammer-like blow, to release theclamping force and enable the wire to be withdrawn from the clamps.

It will be observed that a clamp constructed in accordance with theinvention is comparatively inexpensive since all the parts are easilymade and require no drilling, tapping or other similar operations.Moreover, the clamp is easy to assemble and disassemble but, at the sametime, the parts are securely held in their operative positions duringservice use. In addition, the clamp when used with the manufacture ofprestressed concrete beams is protected against fouling which mightotherwise be caused by concrete splashings.

We claim as our invention:

1. A wire clamp comprising an elongated clamp body having a pair ofopposed walls and a bottom surface defining an upwardly directedtransverse slot in said clamp body, a first jaw member positioned insaid slot against one of said walls and the slot bottom, said jaw memberhaving a wire gripping surface and an upward- 1y chamfered surfaceextending therefrom, a pair of shoulders depending from said jaw memberand slidably engaging the sides of said body, a second jaw memberpositioned in said slot adjacent said first jaw member and having on oneside a wire gripping surface and a chamfered surface extending upwardlytherefrom opposed to the corresponding surfaces on said first jawmember, a pair of shoulders depending from said second jaw member andslidably engaging the sides of said body, said second jaw member havingon the opposite side a surface tapered with respect to the wire grippingsurface, a wedge block member interposed between said second jaw memberand the other slot wall and having a tapered surface corresponding tosaid tapered surface on said second jaw member, flanges projectinginwardly from each of said walls over the members adjacent thereto, anda flange on said wedge block member extending over said second jawmember, said flanges holding said jaw members and said block in saidslot.

2. In a wire clamp, the combination of, a clamp body defining anupwardly directed slot having vertical trans verse walls, a pair of jawmembers positioned in said slot adjacent one wall for gripping a wireand having end portions depending alongside said body, one of said jawshaving a tapered wedge surface, a wedge block in said slot between saidjaws and the other wall and having a wedge surface cooperable with saidjaw wedge surface upon relative sliding movement with respect thereto tourge the jaws together into gripping engagement with the wire, shouldermembers on said clamp body overhanging said walls, and a shoulder memberon said wedge block overhanging said tapered surface, said shouldermembers normally preventing removal of the jaw members and wedge blockfrom said slot.

3. In a wire clamp, the combination of, a clamp body defining a slot, :1pair of jaw members positioned in said slot for gripping a wire, one ofsaid jaw members having a tapered wedge surface, a wedge block disposedin said slot adjacent said one jaw member and having a wedge surfacecooperable with said jaw wedge surface upon relative sliding movementwith respect thereto to urge the jaws together into gripping engagementwith the wire, a first shoulder member on said clamp body overhangingsaid wedge block, a second shoulder member on said wedge blockoverhanging the adjacent one of said jaw members, and a third shouldermember on said body and overhanging the other of said jaw members, saidshoulder members normally preventing said jaw members and said blockfrom being removed from said slot.

4. in a wire clamp, the combination of, a clamp body defining anupwardly opening inverted T-shaped slot formed by a pair of verticaltransverse walls and opposed members overhanging said walls, a pair ofjaw members positioned in said slot with one of said jaws adjacent oneof said walls and below one of said overhanging members, said jawmembers having opposed gripping surfaces for holding a Wire and havingend portions depending alongside said clamp body, the other of said jawmembers having a tapered wedge surface, an L-shaped wedge block havingone leg positioned in said slot between said other jaw and the oppositeslot wall and beneath the other of said overhanging members, the otherleg of said block overhanging said other jaw and said block having endportions depending alongside said clamp body, said wedge block furtherhaving a tapered wedge surface cooperable with said jaw wedge surface tourge the latter into gripping engagement with a wire upon relativetransverse sliding movement between said wedge block and said jaw.

5. in a Wire clamp, the combination, a clamp body defining an upwardlyopening inverted T-shaped slot formed by a pair of vertical transversewalls and opposed members overhanging said walls, a pair of jaw memberspositioned in said slot with a first one of said jaw members adjacentone of said walls and below a first one of said overhanging members,said jaws having gripping surfaces for holding a wire and having endportions depending alongside said clamp block, the second of said jawshaving a tapered wedge surface, an L-shaped wedge block having one legpositioned in said slot between said second jaw and the opposite slotwall and beneath the second one of said overhanging members, the otherleg of said block overhanging said one jaw and said block having endportions depending alongside said clamp body, said wedge block beingnarrower at one end to provide a tapered wedge surface cooperable withsaid jaw wedge surface to urge the latter into gripping engagement witha wire upon relative transverse sliding movement between said wedgeblock and said jaw, said first jaw being movable out from under saidfirst overhanging member when the narrow end of said wedge block engagessaid second jaw.

6. In a wire clamp, the combination of, a clamp body having an upwardlyopening slot defined by spaced vertical walls and a bottom surface,first and second jaws disposed in said slot with said first jaw againstone of said walls, said jaws having opposed faces for gripping a wire,the back of said second jaw having a tapered wedge surface, a wedgedisposed in said slot between said second jaw and the other of saidwalls and having narrow and wide ends to define a wedge surfacecooperating with the wedge surface on said second jaw thereby to urgethe second jaw toward the first jaw, a first flange projecting laterallyfrom said one Wall to overlie said first jaw, a second flange projectinglaterally from said other wall to overlie said wedge, and a third flangeprojecting laterally from said wedge to overlie said second jaw wherebysaid three flanges retain said jaws and said wedge in said slot.

7. in a wire clamp, the combination of, a clamp body having an upwardlyopening slot defined by spaced vertical walls and a bottom surface,first and second jaw-s disposed in said slot with said first jaw againstone of said walls, said jaws having opposed faces for gripping a wire,the back of said second jaw having a tapered wedge surface, a wedgedisposed in said slot between said second jaw and the other of saidwalls and having narrow and wide ends to define a wedge surfacecooperating with the wedge surface on said second jaw thereby to urgethe second jaw toward the first jaw, a first flange projecting laterallyfrom said one wall to overlie said first jaw, a second flange projectinglaterally from said other wall to overl e said wedge, and a third flangeprojecting laterally from said wedge to overlie said second jaw wherebysaid three flanges retain said jaws and said wedge in said slot, saidfirst jaw being movable in under the space between said first and secondflanges when the narrow end of said wedge engages said second jaw.

S. In a wire clamp, the com ination of, a clamp body having an upwardlyopening slot defined by spaced vertical walls and a bottom surface,first and second jaws disposed in said slot with said first jaw againstone of said walls, said jaws having opposed faces for gripping a wire,the back of said second jaw having a tapered wedge surface, a wedgedisposed in said slot between said second jaw and the other of saidwalls and having narrow and wide ends to define a wedge surfacecooperating with the wedge surface on said second jaw thereby to urgethe second jaw toward the first jaw, a first flange projecting laterallyfrom said one wall to overlie said first jaw, a second flange projectinglaterally from said other wall to overlie said wedge, and a third flangeprojecting laterally from said wedge to overlie said second ja-w wherebysaid three flanges retain said jaws and said wedge in said slot, saidfirst and second flanges defining a space slightly larger than theoverall width of said wedge and said first jaw being movable in undersaid space when the narrow end of said wedge engages said second jaw.

References {Zited in the file of this patent UNITED STATES PATENTS769,878 Sturgis Sept. 13, 1904 1,079,646 Hansen Nov. 25, 1913 1,793,140Steinmayer Feb. 17, 1931 2,204,979 Buchanan June 18, 1940 2,245,316Amsler June 10, 1941 2,318,507 Martin May 4, 1943 2,548,712 Firmin Apr.10, 1951 2,729,869 Huyser Jan. 10, 1956

3. IN A WIRE CLAMP, THE COMBINATION OF, A CLAMP BODY DEFINING A SLOT, APAIR OF JAW MEMBERS POSITIONED IN SAID SLOT FOR GRIPPING A WIRE, ONE OFSAID JAW MEMBERS HAVING A TAPERED WEDGE SURFACE, A WEDGE BLOCK DISPOSEDIN SAID SLOT ADJACENT SAID ONE JAW MEMBER AND HAVING A WEDGE SURFACECOOPERABLE WITH SAID JAW WEDGE SURFACE UPON RELATIVE SLIDING MOVEMENTWITH RESPECT THERETO TO URGE THE JAWS TOGETHER INTO GRIPPING ENGAGEMENTWITH THE WIRE, A FIRST SHOULDER MEMBER ON SAID CLAMP BODY OVERHANGINGSAID WEDGE BLOCK, A SECOND SHOULDER MEMBER ON SAID WEDGE BLOCKOVERHANGING THE ADJACENT ONE OF SAID JAW MEMBERS, AND A THIRD SHOULDERMEMBER ON SAID BODY AND OVERHANGING THE OTHER OF SAID JAW MEMBERS, SAIDSHOULDER MEMBERS NORMALLY PREVENTING SAID JAW MEMBERS AND SAID BLOCKFROM BEING REMOVED FROM SAID SLOT.